Improved Frequency-Temperature Characteristics of Quartz Crystal Units

摘要

Efforts concerned an investigation of techniques of reducing the frequency drift with temperature of a quartz resonator by means of a temperature-dependent stress applied to the resonator plate. Two different methods for the temperature compensation of an AT type quartz resonator by means of stresses applied to the crystal plate were explored. The first method employs compressional and extensional stresses in the Z direction. The second method utilizes a flexural strain about the X-axis. Compensated resonators of both types were fabricated and tested. These exhibit improved frequency stability as compared to uncompensated resonators. The goal of plus or minus 1 ppm was achieved over the entire -40 to +80 C range with some units utilizing the second compensation method. The majority of a quantity of forty sealed units had a tolerance of plus or minus 2.0 ppm or better over the same range. The feasibility of using the second method of compensation to produce a compensated holder of the HC-6/U type was proved. The results of shock and vibration tests were favorable. An investigation into the basic repeatability of the uncompensated F-T characteristics revealed an aging effect induced by repeated F-T runs and indicated that the basic repeatability may be only about plus or minus 0.5 ppm. (Author)